I recently bought a 2 bay self serve. This is my first wash. On one bay the pressure would not go above 300. I changed the unloader, the gauge and put a new gun and tip on in the bay. That seemed to fix the problem for about a week. During that week however I noticed it would have 1100 psi and other times it would only seem to be making 300 again. Now its back to 300. No amount of adjustment on the unloader moves the needle. I did just notice that one of the belts shredded. So I'm shutdown to replace them. Would losing 1 belt change my pressure? What am I missing?
Cat 310 pressure regulation
- Thread starter AMWeber
- Start date
MEP001
Well-known member
There could be any of a number of things wrong. The pump could need seals and/or valve o-rings, you could have a restriction on the inlet, there could be air entering the pump from a leak, there could be a bad check valve somewhere allowing some flow to be lost. If you can, set a camera or phone in the room pointing at the pump and gauge to record while you run the bay and pull/release the trigger about every five seconds and post it here. Also (without recording) do the same thing for a few cycles but on EACH high-pressure selection and take note of how the pump runs.
Toms PTcarwash
Active member
I am surprised you have more than one belt to drive a 310. If it is a new to you wash, I would get new seals and valves for the pumps and rebuild them so you have a solid starting point. Make sure the brass seal casings are not scored. Also new belts and fresh cat oil in the pumps. Before you turn them on again, make sure your supply water to the pump is consistent. These pumps are pretty bullet proof, unless they run dry. It only takes a minute or less of water starvation to trash the seals and casings.
Twodose
Active member
Make sure no cavitation before replacing the HP, LP seals.
https://www.catpumps.com/310-service-videos < watch the videos.
https://www.catpumps.com/310-service-videos < watch the videos.
I.B. Washincars
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If it's been cavitating for any length of time, the head could be washed out. Check it for washout in both the seal mating surfaces and the valve bores. Throwing a couple hundred dollars worth of parts into a washed out head is money thrown away. I'm not saying cavitation is your issue, but just throwing random, expensive, parts at it without thoroughly checking it is not wise. Another thing...if you have a seal or valve problem, most likely the pump will pulsate.
here is a video of the gauge when the pump is running. I’m in the bay with the cycling the wand. The pressure is high when closed and falls to about 300 when the trigger is pulled.
View attachment trim.9AFCBFAA-72DF-48B4-AF3A-5EFA87032D39.MOV
View attachment trim.9AFCBFAA-72DF-48B4-AF3A-5EFA87032D39.MOV
MEP001
Well-known member
That could be a check valve. The pump is smooth and quiet. It's not cavitating and it loses pressure immediately with the trigger pulled, so it's not a restriction of supply or a leak allowing air. There's a check valve right at the pump in your video. Disconnect that line to it and see if water is coming out from it. That one is probably your weep, and there will be at least one more at the boom you need to check. Once you either find or eliminate those as the problem, it's time to open up the pump. Check all the valves first, make sure there is no debris under the poppet and the o-rings and backup rings are good.
edredtop
Well-known member
The pump is able to produce 1,100 psi when it's in unload mode (closed cycle) leading one to believe the seals are fine. That would just leave a restriction downstream from the pump to the trigger because of a pressure drop when the trigger is pulled. There's enough flow to activate the unloader, but not enough to operate at the desired pressure.
A simple test would be to install a new hose and gun at the unloader and test it in the equipment room by squirting it in the drain.
Doing that takes everything out of the loop right up to the pump, minus the unloader.
It would be interesting to see how the unloader has been connected as well because it seems to be producing desired pressure when the trigger isn't pulled, and regulated pressure when it is pulled.... weird.
If you look at how clean his pumps are, and then the fresh belt shavings under this pulley, and his revelation of the problem with a belt at another pulley, it seems like a new problem has recently developed that's making the pumps work harder than normal.
Possibly even a blockage at the inlets?
